Infection due to a novel mycobacterium, mimicking multidrug-resistant Mycobacterium tuberculosis

An early and trustable indicator suggestive of non-tuberculosis mycobacteria isolation in a high tuberculosis burden setting

BACKGROUND

Distinguishing between nontuberculous mycobacterial (NTM) lung infections and pulmonary tuberculosis becomes challenging due to their similar clinical manifestations and radiological images. Consequently, instances of delayed diagnosis or misdiagnosis are highly frequent. A feasible and reliable indicator of the existence of NTM in the early stages of the disease would help to solve this dilemma.

METHODS

In this study, we evaluated the potential of smear-positive and Xpert assay (Cepheid, USA) negative outcomes as an early indicator of possible NTM infection in a high TB-burden setting retrospectively and prospectively.

RESULTS

During the study period, 12·77% (138/1081) of the smear-positive cases yielded negative outcomes with the simultaneous Xpert assay. From the 110 patients who yielded smear-positive/Xpert-negative outcomes and cultivated strain as well, 105 (95·45%) were proved to have NTM isolated. By incorporating an additional criterion of a negative result from the Interferon-gamma release assay, the accuracy of the screening method reached 100%. Regarding the NTM presence prediction value, smear-positive/Xpert-negative has a sensitivity of 24·86% (45/181) in all NTM isolated cases but 93·75-96·55% accuracy in retrospective study or 93·75% accuracy in prospective study in smear-positive NTM isolated cases. In addition, the specificity was ∼99·47% (943/948) in smear-positive tuberculosis cases.

CONCLUSION

The clue of the presence of NTM could be obtained on the first day of the hospital visit due to the point of care (POC) feature of smear testing and Xpert assay. About one-fourth of the NTM-isolated patients would benefit from this rapid, convenient, and reliable screening strategy in the given circumstance. Smear-positive/Xpert-negative outcome is an early, trustable indicator that is indicative of NTM isolation.

Fifteen years of phenotypic and genotypic surveillance and antibiotic susceptibility pattern of Actinomycetes (Mycobacterium, Nocardia, Rhodococcus, etc.) in clinical and environmental samples of Iran

Actinomycetes, ubiquitous in the natural world, have been known to inflict infections upon both immunocompromised and healthy individuals. Interestingly enough, these species are oftentimes found residing within the microbiota of humans and animals alike. Unfortunately, these infections are frequently misdiagnosed as more sinister ailments such as malignancy or tuberculosis. Due to this issue, this review deals with 15 years of study on clinical and environmental samples to determine Actinomycetes' prevalence, isolation, identification, and antibiotic susceptibility pattern in Iran by Davood Azadi et al. According to the Davood Azadi framework, we searched the following databases: PubMed/MEDLINE, Embase, Scopus, Web of Science, SID, and Google Scholar in the period from 2007 to 2023. This review aimed to provide an overview of the most recent techniques for collecting environmental samples, cultivating them, and identifying the Actinomycetes group's members. The isolation of Actinomycetes from clinical and ecological sources is becoming more prevalent and should be a concern for health authorities in developing countries. Health centers should take action to increase awareness of diagnostic criteria and management guidelines for actinomycete diseases. Improvements in national and regional reference laboratories may also aid in accurately diagnosing these diseases.

Doubled Nontuberculous Mycobacteria Isolation as a Consequence of Changes in the Diagnosis Algorithm

Background

Nontuberculous mycobacteria (NTM) and their associated diseases remain neglected. Through minor modifications in our diagnostic algorithm, we observed an unexpected higher number of cultivable NTM isolates. Therefore, a retrospective study was performed thoroughly to investigate the effect of changed laboratory procedures on NTM isolation in a specialized tuberculosis hospital.

Methods

NTM isolation rates and composition of NTM species were compared for the two diagnostic algorithms: (1) by using traditional p-nitrobenzoic acid (PNB) selective medium as a preliminary test to identify NTM isolates among the positive cultures (procedure I) and (2) by using the MPT64 antigen detection method to distinguish between Mycobacterium tuberculosis complex (MTBC) isolates and possible NTM isolates after a positive MGIT960 liquid culture (procedure II).

Results

The NTM isolation rate in procedure II was significantly higher than the procedure I (18.08% vs 9.71%; P<0.001). A noticeable increase in the ratio of NTM isolates among the identified mycobacteria was observed over the studied years (ie, from 58.18% in 2019 to 72.93% in 2021), which indicated a more precise prescription of species identification test after prompt information was provided in procedure II. In addition, the consistency of the identified species using multiple specimens from the same patient did not present a significant difference between the procedures.

Conclusion

According to our study, NTM infection might be far more underestimated than it is. A diagnostic procedure combining MGIT960 culture and MPT64 antigen detection could timely and easily identify clues of NTM isolates and improve the diagnosis of NTM infections.

Simultaneous Detection of Mycobacterium tuberculosis and Atypical Mycobacteria by DNA-Microarray in Egypt

BACKGROUND AND OBJECTIVES

Immunocompromised patients are a high-risk group for developing mycobacterial infections with either pulmonary and/or extrapulmonary diseases. Low-cost/density DNA-microarray is considered an easy and efficient method for the detection of typical and atypical mycobacterial species.

MATERIALS AND METHODS

Thirty immunocompromised patients were recruited to provide their clinical specimens (sputum, serum, urine, and lymph node aspirates). Real-time polymerase chain reaction (PCR) and DNA-microarray techniques were performed and compared to the conventional methods of Ziehl-Neelsen staining and Lowenstein Jensen culturing.

RESULTS

Mycobacterium tuberculosis complex was detected in all 30 clinical specimens (100% sensitivity) by real-time PCR and DNA-microarray. Additionally, coinfection with 4 atypical species belonging to nontuberculous mycobacteria was identified in 7 sputum specimens. These atypical mycobacterial species were identified as M. kansasii 10% (n = 3), M. avium complex 6.6% (n = 2), M. gordanae 3.3% (n = 1), and M. peregrinum 3.3% (n = 1).

CONCLUSION

This study documents the presence of certain species of atypical mycobacteria among immunocompromised patients in Egypt.

Effect of Mixed Infections with Mycobacterium tuberculosis and Nontuberculous Mycobacteria on Diagnosis of Multidrug-Resistant Tuberculosis: A Retrospective Multicentre Study in China

Background

Correct species identification is essential before initiation of TB treatment, due to substantial drug susceptibility profile differences among mycobacterial species. Given that nontuberculous mycobacteria (NTM) are frequently resistant to first-line anti-tuberculosis drugs, cases with mixed infections with Mycobacterium tuberculosis (MTB) and NTM tend to be diagnosed as multidrug-resistant tuberculosis (MDR-TB) cases. Here we report results of a retrospective multicentre study that was conducted to determine the prevalence of TB-NTM infections in previously diagnosed laboratory-confirmed multidrug-resistant tuberculosis (MDR-TB) patients using phenotypic drug susceptibility testing. The results were then used to identify risk factors associated with susceptibility to mixed infections.

Methods

From January 2019 through December 2019, we retrospectively collected MDR-TB isolates from three TB specialised hospitals. Species identifications of isolates were performed using the MeltPro Myco assay.

Results

A total of 837 MDR-TB isolates were analysed, of which 22 isolates (2.6%) were found to contain a mixture of NTM and MTB organisms. Significant differences in prevalence rates of mixed infections across regions were observed, with prevalence rates ranging from 0.0% (0/213) in Beijing to 3.4% (12/353) in Fuzhou to 3.7% (10/271) in Guangzhou. Among the 22 patients with NTM-TB mixed infections, a total of five different mycobacterial species were identified, of which the most prevalent species was Mycobacterium intracellulare. Notably, a history of previous TB episodes correlated with higher mixed infection risk.

Conclusion

The results reported here demonstrated that mixed infections with MTB and NTM occurred in approximately 3% of suspected MDR-TB patients in China. These findings raise concerns about the accuracy of molecular diagnostics-based species identification tests and draw attention to the possibility that NTM-MTB mixed infections will be misdiagnosed as MDR-TB in high TB burden settings.

Linezolid for drug-resistant pulmonary tuberculosis

BACKGROUND

Linezolid was recently re-classified as a Group A drug by the World Health Organization (WHO) for treatment of multi-drug resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB), suggesting that it should be included in the regimen for all patients unless contraindicated. Linezolid use carries a considerable risk of toxicity, with the optimal dose and duration remaining unclear. Current guidelines are mainly based on evidence from observational non-comparative studies.

OBJECTIVES

To assess the efficacy of linezolid when used as part of a second-line regimen for treating people with MDR and XDR pulmonary tuberculosis, and to assess the prevalence and severity of adverse events associated with linezolid use in this patient group.

SEARCH METHODS

We searched the following databases: the Cochrane Infectious Diseases Specialized Register; CENTRAL; MEDLINE; Embase; and LILACS up to 13 July 2018. We also checked article reference lists and contacted researchers in the field.

SELECTION CRITERIA

We included studies in which some participants received linezolid, and others did not. We included randomized controlled trials (RCTs) of linezolid for MDR and XDR pulmonary tuberculosis to evaluate efficacy outcomes. We added non-randomized cohort studies to evaluate adverse events.Primary outcomes were all-cause and tuberculosis-associated death, treatment failure, and cure. Secondary outcomes were treatment interrupted, treatment completed, and time to sputum culture conversion. We recorded frequency of all and serious adverse events, adverse events leading to drug discontinuation or dose reduction, and adverse events attributed to linezolid, particularly neuropathy, anaemia, and thrombocytopenia.

DATA COLLECTION AND ANALYSIS

Two review authors (BS and DC) independently assessed the search results for eligibility and extracted data from included studies. All review authors assessed risk of bias using the Cochrane 'Risk of bias' tool for RCTs and the ROBINS-I tool for non-randomized studies. We contacted study authors for clarification and additional data when necessary.We were unable to perform a meta-analysis as one of the RCTs adopted a study design where participants in the study group received linezolid immediately and participants in the control group received linezolid after two months, and therefore there were no comparable data from this trial. We deemed meta-analysis of non-randomized study data inappropriate.

MAIN RESULTS

We identified three RCTs for inclusion. One of these studies had serious problems with allocation of the study drug and placebo, so we could not analyse data for intervention effect from it. The remaining two RCTs recruited 104 participants. One randomized 65 participants to receive linezolid or not, in addition to a background regimen; the other randomized 39 participants to addition of linezolid to a background regimen immediately, or after a delay of two months. We included 14 non-randomized cohort studies (two prospective, 12 retrospective), with a total of 1678 participants.Settings varied in terms of income and tuberculosis burden. One RCT and 7 out of 14 non-randomized studies commenced recruitment in or after 2009. All RCT participants and 38.7% of non-randomized participants were reported to have XDR-TB.Dosing and duration of linezolid in studies were variable and reported inconsistently. Daily doses ranged from 300 mg to 1200 mg; some studies had planned dose reduction for all participants after a set time, others had incompletely reported dose reductions for some participants, and most did not report numbers of participants receiving each dose. Mean or median duration of linezolid therapy was longer than 90 days in eight of the 14 non-randomized cohorts that reported this information.Duration of participant follow-up varied between RCTs. Only five out of 14 non-randomized studies reported follow-up duration.Both RCTs were at low risk of reporting bias and unclear risk of selection bias. One RCT was at high risk of performance and detection bias, and low risk for attrition bias, for all outcomes. The other RCT was at low risk of detection and attrition bias for the primary outcome, with unclear risk of detection and attrition bias for non-primary outcomes, and unclear risk of performance bias for all outcomes. Overall risk of bias for the non-randomized studies was critical for three studies, and serious for the remaining 11.One RCT reported higher cure (risk ratio (RR) 2.36, 95% confidence interval (CI) 1.13 to 4.90, very low-certainty evidence), lower failure (RR 0.26, 95% CI 0.10 to 0.70, very low-certainty evidence), and higher sputum culture conversion at 24 months (RR 2.10, 95% CI 1.30 to 3.40, very low-certainty evidence), amongst the linezolid-treated group than controls, with no differences in other primary and secondary outcomes. This study also found more anaemia (17/33 versus 2/32), nausea and vomiting, and neuropathy (14/33 versus 1/32) events amongst linezolid-receiving participants. Linezolid was discontinued early and permanently in two of 33 (6.1%) participants who received it.The other RCT reported higher sputum culture conversion four months after randomization (RR 2.26, 95% CI 1.19 to 4.28), amongst the group who received linezolid immediately compared to the group who had linezolid initiation delayed by two months. Linezolid was discontinued early and permanently in seven of 39 (17.9%) participants who received it.Linezolid discontinuation occurred in 22.6% (141/624; 11 studies), of participants in the non-randomized studies. Total, serious, and linezolid-attributed adverse events could not be summarized quantitatively or comparatively, due to incompleteness of data on duration of follow-up and numbers of participants experiencing events.

AUTHORS' CONCLUSIONS

We found some evidence of efficacy of linezolid for drug-resistant pulmonary tuberculosis from RCTs in participants with XDR-TB but adverse events and discontinuation of linezolid were common. Overall, there is a lack of comparative data on efficacy and safety. Serious risk of bias and heterogeneity in conducting and reporting non-randomized studies makes the existing, mostly retrospective, data difficult to interpret. Further prospective cohort studies or RCTs in high tuberculosis burden low-income and lower-middle-income countries would be useful to inform policymakers and clinicians of the efficacy and safety of linezolid as a component of drug-resistant TB treatment regimens.

Pulmonary Isolation of Multidrug resistant "Mycobacterium simulans" and Mycobacterium tuberculosis from a patient in the Horn of Africa

In low-income countries of the Horn of Africa, pulmonary infections are usually considered as tuberculosis, which diagnosis relies on clinical data and positive microscopic observation. This strategy allows non-tuberculous mycobacteria to escape detection, facilitating their emergence in populations. A non-tuberculous mycobacterium strain FB-527 was unexpectedly cultured from the sputum of a Djiboutian patient otherwise diagnosed with multi-drug resistant (MDR) tuberculosis. The sequencing of the rpoB and 16S rRNA genes showed that the isolate was identical to strain FI-09026 previously named "Mycobacterium simulans" and reported only once from a Somali patient. Strain FB-527 mimicked Mycobacterium tuberculosis colonies and enzymatic profile using API ZYM strip and was in vitro resistant to rifampicin and isoniazid. Isolation of two MDR mycobacteria complicated the diagnosis and therapeutic management of the patient. We here report on the complete description of strain FB-527 and strain FI-09026 including genome sequencing, finalizing the description of the proposed new species "Mycobacterium simulans".

Mycobacterium decipiens sp. nov., a new species closely related to the Mycobacterium tuberculosis complex

Two mycobacterial strains with close similarity to the Mycobacterium tuberculosis complex (MTBC) were isolated from cutaneous lesions of patients in the USA and Italy. At the phenotypic level, similarities to the MTBC included slow growth rate, rough morphotype of the unpigmented colonies and nearly identical high-performance liquid chromatography profiles of mycolic acids. In contrast to the MTBC, the strains were niacin- and nitrate-negative, and catalase-positive both at 68 °C and in semi-quantitative tests. The clinical isolates were more closely related to M. tuberculosis than to any other known mycobacterium and scored positive with commercial DNA probes (Hologic AccuProbe M. tuberculosis). Both average nucleotide identity and genome-to-genome distance suggested the strains are different from the MTBC. Therefore, given the distinguishing phenotypic and genomic-scale differences, we submit that the strains belong to a new species we have named Mycobacteriumdecipiens with type strain TBL 1200985^T (=ATCC TSD-117^T=DSM 105360^T).

Mycobacteriosis and Tuberculosis: Laboratory Diagnosis

Background

Tuberculosis is one of the most important infectious diseases that has claimed its victims throughout much of known human history. With Koch's discovery of the tubercle bacillus as the etiologic agent of the disease, his sanitary and hygienic measures, which were based on his discovery and the development of a vaccine against tuberculosis by Albert Calmette and Camille Guérin in 1921, an attenuated Mycobacterium bovis strain, bacilli Calmette-Guérin (BCG), and the discovery of the first antibiotic against tuberculosis, streptomycin by Selman Waksman in 1943, soon led to the opinion that appropriate control measures had become available for tuberculosis and it had been assumed that the disease could ultimately be eradicated.The emergence of resistant strains of this bacteria and widespread distribution of the disease in the world, and the emergence of the AIDS epidemic destroyed any possibility of global control of tuberculosis in the foreseeable future.

Objectives

The purpose of this review is to highlight the current scientific literature on mycobacterial infections and provide an overview on the laboratory diagnosis of tuberculosis and non-tuberculosis infections based on conventional phenotypic and modern molecular assays.

Method

In this study, a number of 65 papers comprising 20 reviews, 9 case reports, and 36 original research in association with mycobacteriosis and the laboratory diagnosis of mycobacterial infections, were reviewed.

Results

Based on our analysis on the published documents methods applied for the laboratory diagnosis of tuberculosis are continually assessed and developed in order to achieve more rapid, less expensive, and accurate results. Acid-fast staining and culture for mycobacteria remain at the core of any diagnostic algorithm with the sensitivity of 20-70% and specificity of 95-98% for AFB microscopy and the sensitivity of 95% and the specificity of 98% for culture based diagnosis. Following growth in culture, molecular tests such as nucleic acid hybridization probes and DNA sequencing may be used for definitive species identification. Nucleic acid amplification methods provide the means for direct detection of Mycobacterium tuberculosis in respiratory specimens without the prerequisite to isolate or culture the organism, leading to more rapid diagnosis and better patient care.

Conclusion

As the researchers in a developing country, we strongly believe that despite significant advances in laboratory capacity, in many countries reliable confirmation of suspected mycobacterial diseases is hindered by a lack of knowledge on proper standardized methods, sufficient funds, suitably trained staff and laboratory supplies.

Extended spectrum of antibiotic susceptibility for tuberculosis, Djibouti

In the Horn of Africa, there is a high prevalence of tuberculosis that is reported to be partly driven by multidrug-resistant (MDR) Mycobacterium tuberculosis strictu sensu strains. We conducted a prospective study to investigate M. tuberculosis complex species causing tuberculosis in Djibouti, and their in vitro susceptibility to standard anti-tuberculous antibiotics in addition to clofazimine, minocycline, chloramphenicol and sulfadiazine. Among the 118 mycobacteria isolates from 118 successive patients with suspected pulmonary tuberculosis, 111 strains of M. tuberculosis, five Mycobacterium canettii, one 'Mycobacterium simulans' and one Mycobacterium kansasii were identified. Drug-susceptibility tests performed on the first 78 isolates yielded nine MDR M. tuberculosis isolates. All isolates were fully susceptible to clofazimine, minocycline and chloramphenicol, and 75 of 78 isolates were susceptible to sulfadiazine. In the Horn of Africa, patients with confirmed pulmonary tuberculosis caused by an in vitro susceptible strain may benefit from anti-leprosy drugs, sulfamides and phenicol antibiotics.

Mycobacterium riyadhense infections

Mycobacterium riyadhense is a newly described slowly growing, non-tuberculous mycobacterium species. We describe 2 new cases of Mycobacterium riyadhense infections presenting with extra-pulmonary involvement, and reviewed all previously reported cases in the literature. We also describe the spectrum of the disease and explore treatment options based on the experience with the current and previously reported cases.

Microbiological features and clinical relevance of new species of the genus Mycobacterium

Nontuberculous mycobacteria (NTM) are present in the environment, mainly in water, and are occasionally responsible for opportunistic infections in humans. Despite the fact that NTM are characterized by a moderate pathogenicity, the diseases caused by NTM at various body sites are increasing on a worldwide level. Among over 150 officially recognized NTM species, only two or three dozen are familiar to clinicians, and even to most microbiologists. In this paper, approximately 50 new species described in the last 8 years are reviewed, and their role in human infections is assessed on the basis of reported clinical cases. The small number of reports concerning most of the "new" mycobacterial species is responsible for the widespread conviction that they are very rare. Their role is actually largely underestimated, mainly because they often remain unrecognized and misidentified. Aiming to minimize such bias, emphasis has been placed on more common identification pitfalls. Together with new NTM, new members of the Mycobacterium tuberculosis complex described in the last few years are also an object of the present review.

Nontuberculous mycobacteria in Middle East: Current situation and future challenges

Nontuberculous mycobacteria (NTM) are a diverse group of bacterial species that are distributed in the environment. Many of these environmental bacteria can cause disease in humans. The identification of NTM in environmental sources is important for both clinical and epidemiological purposes. In this study, the distribution of NTM species from environmental and clinical samples in the Middle East was reviewed. In order to provide an overview of NTM, as well as recent epidemiological trends, all studies addressing NTM in the Middle East from 1984 to 2014 were reviewed. A total of 96 articles were found, in which 1751 NTM strains were isolated and 1084 of which were obtained from clinical samples, 619 from environmental samples and 48 were cited by case reports. Mycobacterium fortuitum was the most common rapid growing mycobacteria (RGM) isolated from both clinical (269 out of 447 RGM; 60.1%) and environmental (135 out of 289 RGM; 46.7%) samples. Mycobacterium avium complex (MAC) was the most common slow growing mycobacteria (SGM) isolated from clinical samples (140 out of 637 SGM; 21.9%). An increasing trend in NTM isolation from the Middle East was noted over the last 5years. This review demonstrates the increasing concern regarding NTM disease in the Middle East, emphasizing the need for regional collaboration and coordination in order to respond appropriately.

First report of isolation of Mycobacterium canariasense from hospital water supplies

Mycobacterium canariasense was first isolated as a novel species in 2004 from clinical specimens in Spain. Since then there have only been a few additional reports from Spain, the USA, and Lebanon on the isolation of this rare species from clinical specimens. We herein present the first report on isolation of this organism from hospital water, which provides evidence for determining the natural habitat of this rare species. The water samples were collected from hospital departments and cultured on Löwenstein-Jensen and Sauton's media. The isolates, i.e. WP5, WP20, and AW2-3, were subjected to identification by conventional and molecular tests including sequencing analysis of 16S rRNA. The water isolates revealed phenotypic and molecular features consistent with M. canariasense including a genus-specific amplicon of the hsp65 gene and 100% similarities with those of M. canariasense CIP: 107998(T) 16S rRNA gene sequences. The current report might be of value in tracing the probable source of infection in patients.

First report of isolation of Mycobacterium novocastrense from water supplies

We herein present the first documented report associated with the isolation of Mycobacterium novocastrense from environment. The identification and characterization of four unrelated isolates, one from the surface water and the other three from hospital water, were achieved by various conventional and molecular tests including a genus-specific PCR for Mycobacterium based on 65-kDa heat shock protein (hsp) gene and 16S rDNA sequencing. Our findings might shed further light on the natural habitat of this rare Mycobacterium.

Lung infection caused by Mycobacterium riyadhense confused with Mycobacterium tuberculosis: the first case in Korea

A slowly growing, non-chromogenic mycobacterial strain was isolated from sputum and bronchial lavage fluid samples of a patient presenting with productive cough, blood-tinged sputum, low-grade fever, and weakness. A positive acid-fast bacilli sputum smear result prompted the initiation of an anti-tuberculosis regimen. Multiplex real-time PCR showed a negative result for Mycobacterium tuberculosis complex and a positive result for nontuberculous mycobacteria. The DNA chip test confirmed this organism as a member of the genus Mycobacterium, but could not specify the species. Interestingly, the mycolic acid patterns obtained by HPLC nearly overlapped with those of M. simulans. The sequences of the Mycobacterium 16S rRNA gene and 16S-23S internal transcribed spacer region were unique and were found to have 100% similarity with those of M. riyadhense. After a review of the literature, we report this case as the first Korean case of M. riyadhense lung infection.

Chronic pulmonary disease due to Mycobacterium monacense infection: the first case from Iran

We herein report a case in which the recently characterized species Mycobacterium monacense was isolated from the sputum of an Iranian patient. This case represents the first isolation of M. monacense from Iran. The isolate was identified by conventional and molecular techniques. Our findings show that M. monacense infection is not restricted to developed countries.

Demonstration of cord formation by rough Mycobacterium abscessus variants: implications for the clinical microbiology laboratory

In low-income countries some infections caused by nontuberculous mycobacteria are misdiagnosed as multidrug-resistant tuberculosis. In most of these settings the observation of microscopic cords is the only technique used to identify Mycobacterium tuberculosis in the laboratory. In this article we definitively demonstrate that Mycobacterium abscessus, an emerging pulmonary pathogen, also forms microscopic cords.

Commercial DNA probes for mycobacteria incorrectly identify a number of less frequently encountered species

Although commercially available DNA probes for identification of mycobacteria have been investigated with large numbers of strains, nothing is known about the ability of these probes to identify less frequently encountered species. We analyzed, with INNO LiPA MYCOBACTERIA (Innogenetics) and with GenoType Mycobacterium (Hein), 317 strains, belonging to 136 species, 61 of which had never been assayed before. INNO LiPA misidentified 20 taxa, the majority of which cross-reacted with the probes specific for Mycobacterium fortuitum and the Mycobacterium avium-Mycobacterium intracellulare-Mycobacterium scrofulaceum group. GenoType misidentified 28 taxa, most of which cross-reacted with M. intracellulare and M. fortuitum probes; furthermore, eight species were not recognized as members of the genus Mycobacterium. Among 54 strains investigated with AccuProbe (Gen-Probe), cross-reactions were detected for nine species, with the probes aiming at the M. avium complex being most involved in cross-reactions.